Fluid pump having a radially compressible rotor

ABSTRACT

To design the rotor (6, 6′, 6″, 6″′, 60, 60′) as compressible in the radial direction in a fluid pump, in particular for microinvasive medical use, said rotor is configured as stretchable in its longitudinal direction (16) by push elements and pull elements acting axially on it.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/394,429, allowed, which application is a continuation of U.S.application Ser. No. 15/236,763, filed Aug. 15, 2016, now U.S. Pat. No.10,316,853, issued Jun. 11, 2019, which is a continuation of U.S.application Ser. No. 13/261,363, filed Oct. 19, 2012 now U.S. Pat. No.9,416,791, issued Aug. 16, 2016, which is a United States National Stagefiling under 35 U.S.C. § 371 of International Application No.PCT/EP2011/000438, filed Jan. 25, 2011, which claims the benefit of U.S.Provisional Patent Application No. 61/297,858, filed Jan. 25, 2010, andEuropean Patent Application No. 10075040.5, filed Jan. 25, 2010, all ofwhich are incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

The invention is in the field of mechanical engineering, in particularof micromechanics, and specifically relates to fluid pumps having arotor and at least one impeller blade for the predominantly axialconveying of a fluid.

Pumps of this kind can be used in different technical fields,particularly where deployment locations are difficult to access and acompressible rotor can be brought onto site in compressed form and canthere be expanded for efficient operation.

A particularly advantageous application is in the field of medicinewhere pumps of this kind can be introduced in particularly smallconstruction into the body of a patient, for example through bloodvessels, can be expanded at the deployment location, preferably in aventricle, and can be operated there.

To remove the pump, it can usually be compressed again and removedthrough a sluice.

Corresponding compressible pumps are already known in differentconstructions.

A rotor is, for example, known from WO 03/103745 A2 which has a smallerdiameter in a compressed state than in an expanded state and which hasan unfoldable rotor blade which unfolds in operation by the fluidcounterpressure of the fluid. WO 03/103745 moreover discloses a rotorwhich has elements which are axially displaceable with respect to oneanother and whose mutual displacement accompanies the expansion andcompression of a cage surrounding the rotor in the manner of a housing.

Rotors are moreover known from the prior art whose impeller blades areunfoldable for operation and have joints or elastic support parts forthis purpose. The use of so-called memory alloys such as Nitinol is inparticular known which adopt different geometrical shapes in dependenceon the environmental temperature and thereby allow a subsequentdeformation of the rotor after the introduction into a body.

A fluid pump is known from WO 99/44651 having a compressible rotor whichhas a compressible coil which is covered by membrane, comprises a memoryalloy and is held together axially by an elastic band. The coil can becompressed by radial pressure thereon.

A fluid pump is known from WO 94/05347 having a rotor which carriesconveying elements and is fixedly connected to a shaft, with a sleevemoreover being axially displaceably arranged on the shaft by whosedisplacement a housing surrounding the rotor can be stretched lengthwiseand thus radially compressed. A relative movement of the sleeve to theshaft is converted by a lever mechanism into a radial erection of theconveying elements or into a folding down onto the shaft.

A compressible propeller pump with a rotor is known from WO 99/44651having a helicoidal coil and an elastic band spanned centrally andcoaxially therein as well as a membrane spanned between the namedelements as an impeller blade.

Experience has shown that complex constructions for such pumps are alsodifficult to realize and to operate reliably with the desired servicelives due to the small construction.

BRIEF SUMMARY OF THE INVENTION

It is therefore the underlying object of the present invention againstthis background to provide a fluid pump of the initially named kindwhich allows a reliable function of the pump both on the introductionand removal and in regular operation with a simple construction designand at low costs.

The object is achieved by the features of the invention in accordancewith claim 1.

In this respect, the fluid pump in accordance with the inventionprovides a drivable rotor which is rotatable about its longitudinal axisand which has at least one impeller, with the rotor at least partlycomprising an elastically compressible and expandable material and beingelastically stretchable in the direction of its longitudinal axis byelements acting axially on it.

Provision is moreover made in this respect that a push-element and apull-element engage at different ends of the rotor and/or of a housingof the fluid pump.

A transverse contraction can, on the one hand, be directly realized bythe elastic stretchability in the longitudinal direction with such amaterial-elastic rotor which can, for example, partly comprise anelastomer or a foam. However, different mechanisms within the rotor canalso be set into motion by the longitudinal stretching which result in atransverse compression or in an easier transverse compressibility.Provision can e.g. be made for this purpose that the impeller blades arealso stretched in the longitudinal direction of the rotor in that theyare connected to a hub over a certain extent in the longitudinaldirection of said hub. In the non-stretched state, the impeller bladescan have a concave or convex or folded form or correspondingly formedsupport structures in their interior which are stretched by thelongitudinal stretching of the rotor. Such geometrical shapes can givethe blades additional stability with respect to the fluid pressure inoperation, but also with respect to a radial compression, in thenon-stretched state. If such structures are elongated by longitudinalstretching of the rotor, a facilitated deformability of the impellerblades results so that the rotor as a whole either becomes more easilyradially compressible or automatically at least compresses a little on alongitudinal stretching.

A corresponding facilitation of the radial compressibility can thenoptionally be utilized by additional mechanisms of the radialcompression, for example on moving into a sluice.

The described construction with a connection between the impeller bladesand the hub extended in the longitudinal direction is moreover of simpleconstruction to the extent that the rotor and the impeller blades can bemanufactured in one piece, for example, cast or vulcanized.

The rotor can advantageously be arranged at the distal end of a hollowcatheter for the medical deployment of a fluid pump in accordance withthe invention in order to be able to transport it with said hollowcatheter through a bloodstream into a ventricle, for example.

Provision can advantageously be made in this case that a pull can beapplied in mutually opposite directions to both ends of the rotor by twoelements mutually movable and extending along the catheter. The rotorcan thus be extended from the proximal end of the catheter along thecatheter by different mutually displaceable elements.

Provision can advantageously be made in this respect that one of theelements is a jacket and the other element is a core extending in thejacket. On the provision of a jacket and of a core extending therein,these two elements can support one another against outward kinking. Apull can, on the one hand, by applied by means of the jacket and apressure in the longitudinal direction can be applied by means of thecore, or vice versa.

The hollow catheter can advantageously itself serve as a jacket and,optionally, a drive shaft extending therein can also serve as a core.

Alternatively or additionally to this, however, lines can also beintroduced at the outer circumference of the catheter which, with acorresponding stiffness, can transmit both a pull and a compression inthe longitudinal direction or corresponding pull-movements andpush-movements.

These lines can be introduced along the catheter up to the sluicethrough which the catheter is introduced into the body and can extendfurther to the exterior of the body and can be fastened in a fasteningring there so that the lines can be comfortably operated from outsidethe patient's body.

Provision can be made for the more specific embodiment of the inventionthat the proximal end of the rotor is connected to the core and thedistal end of the rotor is connected to a housing of the rotor in apull-resistant manner and that the housing is connected in apressure-resistant manner to the jacket. In this case, the core canapply a pull to the rotor at its proximal end, whereas the other,distal, end of the rotor is held in a housing, for example, in apull-resistant rotary bearing, which applies a pull in a directionopposite to the core to the rotor which can be realized by a support ofthe housing at the distal end of the hollow catheter/of the sleeve as aholding force. A compressive force then has to be applied to the sleevealong the catheter and a corresponding pulling force has to be appliedto the core.

Provision can also advantageously be made that the proximal end of therotor is connected directly, or indirectly via the housing, to thesleeve in a pull-resistant manner and that the distal end of the rotoris connected directly, or indirectly via the housing, to the core in apressure-resistant manner. In this case, a pull-force is applied by thedistal end of the jacket to the proximal end of the rotor, for exampleby a pull-resistant rotary bearing, whereas a pull-force is applied inthe distal direction to the distal end of the rotor by the core whichtransmits a corresponding push-force. The core can for this purposeextend, for example, through the rotor and be connected to the rotor atits distal end. The core can, for example, be formed by a drive shaft ofthe rotor.

A further embodiment of the invention provides that the rotor issurrounded by a housing likewise stretchable in the direction of thelongitudinal axis. In this case, the rotor can in each case be connectedrotatably, but in a pull-resistant manner, at its two ends to thehousing, e.g. in that the rotor is journalled at both sides in thehousing in pull-resistant rotary bearings. If a longitudinal stretchingis then exerted onto the housing, it is transmitted directly to therotor. The rotor is thus either compressed directly in the radialdirection or it is at least more easily compressible.

Provision can particularly advantageously be made in this respect thatthe housing automatically undergoes a longitudinal stretching parallelto the longitudinal axis in the case of a transverse compressionsubstantially perpendicular to the longitudinal axis. Provision canadvantageously be made in this respect that the housing has a bulbousshape with an inner space sufficient for the expanded rotor in the statein which no forces act on it in the longitudinal direction.

In this case, a longitudinal stretching of the housing and thus alongitudinal stretching of the rotor, associated with a transversecontraction or facilitation of the compressibility of the rotor, can beachieved by application of a radial compression onto the housing, thatis, for example, by moving the housing into a funnel-shaped sluice. Forthis purpose, a corresponding sluice which generates a correspondingradial compression on the withdrawal of the pump housing can beprovided, for example, at the end of the hollow catheter. A sluice can,however, also be provided which surrounds the hollow catheter as suchand into which the hollow catheter can be withdrawn for the compressionof the housing. A corresponding sluice can have an inflow funnel for thepump housing for this purpose.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be shown and subsequently described in the followingwith reference to an embodiment in a drawing.

There are Shown

FIG. 1 schematically in an overview, the use of a micropump inaccordance with the invention in a ventricle;

FIG. 2 a three-dimensional view of a rotor in accordance with theinvention in a non-stretched form;

FIG. 3 the view of the rotor of FIG. 2 in a longitudinally stretchedform;

FIG. 4 a view of a further rotor in non-stretched form;

FIG. 5 the rotor of FIG. 4 in a form stretched in the longitudinaldirection;

FIG. 6 a further rotor in a three-dimensional view in a non-stretchedform;

FIG. 7 the rotor of FIG. 6 in a form stretched in the longitudinaldirection;

FIG. 8 highly magnified in a longitudinal section, the structure of amicropump in accordance with the invention with the end of a hollowcatheter;

FIG. 9 a fastening apparatus for lines which run along the catheter formanipulating the pump;

FIG. 10 the arrangement of FIG. 9 in a wedged state;

FIG. 11 a longitudinal section through a rotor in whose central hollowspace a drive shaft extends;

FIG. 12 schematically in a first arrangement, the components of a pumpwhich participate in the application of a longitudinal pull onto therotor;

FIG. 13 a similar arrangement as in FIG. 12 with another principle forthe application of the pull; and

FIG. 14 a third arrangement for applying a longitudinal pull to a rotorusing a further principle.

DETAILED DESCRIPTION

FIG. 1 shows a hollow catheter 1 which is introduced through a sluice 2into a blood vessel 3 of a human body and which is inserted there up tothe ventricle 4. At the distal end of the hollow catheter 1, a pump 5 isfastened having a rotor 6 which rotates about its longitudinal axis andthus conveys blood axially out of the ventricle 4 into the blood vessel3.

The rotor is for this purpose drivable by a motor 7 via a shaft 8 at ahigh speed, typically between 10,000 and 50,000 revolutions per minute.

Blood is sucked in axially by the rotation of the rotor 6 in thedirection of the arrows 9, 10 through the intake openings 11 of the pumpand is expelled again in the direction of the arrows 12, 13 within theblood vessel 3. The activity of the heart in the conveying of blood isthereby replaced or supplemented.

The pump 5 has a housing surrounding the rotor 6 and is radiallycompressible as a whole with respect to the diameter for insertion intothe blood vessel 3.

Once the pump 5 has reached the ventricle 4, it can be radially expandedin that both the housing and the rotor 6 are expanded to achieve ahigher performance capability of the pump by erecting the rotor blades.

It is the object of the present invention to achieve a radialcompressibility of the rotor 6 which is as easy and as simple aspossible.

To illustrate the function of the invention, a rotor 6 having ahelically revolving impeller blade 14 will first be looked at withreference to FIG. 2 . The impeller blade 14 must have a certain minimumstiffness in order not to be folded down onto the hub 15 of the rotor 6by the fluid counterpressure on the conveying of a fluid.

This stiffness generally makes it difficult to achieve a radialcompression or a placing of the impeller blade 14 onto the hub 15 toreduce the diameter of the rotor on the installation of the pump.

In FIG. 3 , the rotor from FIG. 2 is shown in a form stretched in thelongitudinal direction. The hub body 15 can, just like the impellerblades, for example, comprise rubber or another elastomer or a foam oranother compressible and expandable material and is automaticallycompressed on a longitudinal stretching of the rotor by the generalmaintenance of volume.

At the same time, the dimensions of the impeller blade 14 transverselyto the longitudinal direction 16 reduce so that the total dimensions ofthe rotor 6 transverse to the longitudinal direction 16 reduce due to asimultaneous radial compression of the hub body 15 and of the impellerblade 14. The rotor can be transported substantially more easily througha narrow blood vessel in this state than in the expanded state without alongitudinal stretching of the rotor. The total diameter of the rotor isthus easily reduced. In addition, the longitudinal stretching can havean effect on the impeller blades.

FIG. 4 shows another embodiment of the rotor 6′ having impeller blades14′ which are made concave or curved in cross-section to provide theindividual impeller blade with additional stability with respect to aninward kinking due to the fluid counterpressure.

If the corresponding rotor 6′ is stretched in the longitudinal direction16, the illustration as shown in FIG. 5 results in which the diameter ofthe hub body 15′ is reduced and simultaneously the impeller blades 14′are pulled longitudinally in the longitudinal direction 16. The concaveform of the impeller blades 14′ is hereby completely or almostcompletely eliminated so that the stability of each individual impellerblade with respect to a kink movement in the peripheral direction of therotor is much reduced. The stability of the impeller blades is thusreduced and a radial compression by external effect, for example, on acompression of the housing surrounding the rotor is simplified.

In FIG. 6 , another principle of rotor design is shown which can be usedin addition or alternatively to the above-described installations, witha rotor 6″ being equipped with impeller blades 14″ which, in theirinterior, have a stiffening structure 16 in the form of a metal sheet oranother flat material kinked in the manner of saw teeth incross-section. This kinked reinforcement material stiffens the impellerblade 14″ greatly with respect to kinking.

If the rotor 611 is pulled lengthways, the situation as shown in FIG. 7results, with the impeller blade 14″ being pulled lengthways and thusthe angle of engagement being reduced and with the reinforcementstructure 17 simultaneously being pulled longitudinally by thestretching in the longitudinal direction up to the complete eliminationof the kink.

The impeller blade 14″ can hereby be folded onto the hub body 15″ a lotmore easily and the rotor 6″ is thus radially compressed with respect tothe hub body, on the one hand, and can be further compressible even moreeasily with respect to the impeller blades.

FIG. 8 shows a fluid pump 6 having a rotor 6 which has impeller blades18 in a longitudinal section. It is schematically shown that the rotor 6is rotatably journalled in a distal bearing 20 at its distal end 19. Thebearing 20 is fastened to struts 21 of the pump housing 22.

The rotor 6 is rotatably journalled in a proximal bearing 23 at itsproximal end, and indeed by means of a shaft 8 or by means of astiffened connector piece of the shaft 8 at the rotor 6.

The fluid pump 5 sucks in liquid through an intake cage 24 and expels itagain through the openings 25, 26. The pump 5 is arranged at the distalend of a hollow catheter 1 through which the drive shaft 8 extends inthe longitudinal direction. The hollow catheter 1 has an inflow sluice27 in the form of a funnel at its end and the housing 5 can be pulledinto said inflow sluice for the removal of the pump from a patient'sbody. A pulling movement can, for example, be applied to the housing 5by means of the lines 28, 29, with the lines 28 being guided in holdersat the outer side of the hollow catheter, while the line 29 is shown asextending in the interior of the hollow catheter.

When the guide of the lines 28, 29 is tight enough, they cannot only betransferred by a pulling movement, but also by a pushing in thelongitudinal direction.

The lines 28, 29 can, as shown at the bottom of FIG. 8 , be held at theproximal end of the hollow catheter 1, for example in a clamping ring30, which can be displaced or also rotated and fixed as a whole formanipulating the pump 5 along the catheter. The corresponding lines 28are clamped in the clamping ring 30.

In the example shown, the bearing 20 is a pull-resistant rotary bearingso that the distal end of the rotor 6 is not only rotatably journalledin this bearing, but is also held in the longitudinal direction.

The proximal bearing 23 allows a movement of the shaft 8 or of a shaftprolongation in the longitudinal direction so that no pull-resistantconnection is present there.

If a pull is exerted at the drive shaft 8 in the longitudinal directionfrom the proximal end of the hollow catheter, the rotor 6 is subjectedto a longitudinal stretching which results in a transverse compression.

It is also conceivable to exert radial pressure onto the housing 5 inthe direction of the arrows 31, 32 and thus to achieve a longitudinalstretching of the housing which can be transmitted to the rotor 6 inthat the housing abuts the abutment 33 fixedly connected to the shaft 8or at least fixed in the longitudinal direction with respect to theshaft 8 in the region of the proximal bearing 23 and also pulls therotor lengthways on a further longitudinal stretching of the housing.

An automatic transverse compression of the rotor thereby results so thatthe rotor can simply also be compressed as part of the compression ofthe housing 5.

In FIG. 9 , the function of the clamping ring 30 is shown in a schematicmanner which has an outer part ring 34 and an inner part ring 35, eachof which part rings have conical boundary surfaces 36, 37. If the outerpart ring 34 is moved in the direction of the arrow 38 with respect tothe inner part ring 35, the image shown in FIG. 10 results in which theconical surfaces 36, 37 come into contact with one another and wedgetogether. The lines 28 arranged between them are clamped in thisconnection and are fixed in the longitudinal direction.

The total clamping ring 30 can then be moved for manipulating the lines28.

The diameter-reduced state and the expanded state could in each casealso be locked independently of one another with the aid of an apparatuswhich is not further embodied.

FIG. 11 schematically shows a special embodiment of the rotor 6′″ whichhas a central hollow space 39 through which the drive shaft 8 extendslengthways from the proximal end 40 of the rotor to the distal end 41.The drive shaft 8 is connected via a mount body 42 in a rotationallyfixed and pull-resistant manner to the rotor at the distal end 41 sothat the rotor 6′″ can be driven via the shaft 8 from the proximal end40. At the same time, however, the rotor 6′″ can be connected in apull-resistant manner to the shaft 8 at the proximal end 40 in thepulling direction which is indicated by the arrows 43.

The rotor is journalled there in a rotatable and pull-resistant mannerin the proximal bearing 23 so that, when a pressure is applied onto theshaft 8 in the direction of the arrow 44, the rotor is pulled lengthwaysbetween the mount body 42 and the bearing 23. The rotor 6 1 ″ can herebybe compressed in the transverse direction.

FIGS. 12, 13 and 14 generally show different principles according towhich a longitudinal pull can be applied to a rotor in similarembodiments. In this respect, the housing is designated by 50 in FIG. 12. Said housing surrounds the rotor 60 and is supported on the distal endof the hollow catheter 1.

A pressure can thus be transmitted in the direction of the arrow 51 viathe hollow catheter 1 onto the housing 50 whose distal end 52 can exerta pull onto the rotor 60 in the direction of the arrow 54 via thepull-resistant bearing 53.

The drive shaft 8 is rotationally fixedly connected to the proximal endof the rotor 60. Said proximal end can moreover, which is not shown indetail, be axially displaceably rotatably journalled at the housing 50or at the hollow catheter 1. If a pull is exerted onto the drive shaft 8in the direction of the arrow 55 and if the hollow catheter issimultaneously supported, the rotor 60 is stretched in the longitudinaldirection.

It is shown with reference to FIG. 13 that a transverse pressure canalso be exerted onto the housing 50 perpendicular to the longitudinaldirection, shown by the arrows 56, 57, said transverse pressureresulting in a longitudinal stretching of the housing 50 in thedirection of the longitudinal axis 16 due to the bulbous embodiment ofthe housing which is stiff to a certain extent. The housing can comprisea hose, for example made from an elastomer or from longitudinal barswhich are covered by a membrane or are surrounded by a deformable hose.The distal end of the housing 50 expands in the direction of the arrow58. A corresponding pull is exerted onto the rotor 60 in the directionof the arrow 59 via the pull-resistant rotary bearing 53. The housing 50lengthens so far in the direction of the longitudinal axis 16 until itsproximal end 61 abuts the abutment 62 which is non-displaceablyconnected to the drive shaft 8. On a corresponding further expansion ofthe housing 50 in the longitudinal direction, a pull is exerted onto thedrive shaft 8 by means of the abutment 62 which results in alongitudinal stretching of the rotor 60.

Alternatively, the abutment 62 can also be omitted provided that a pullis applied to the proximal end of the rotor by means of the drive shaft8.

FIG. 14 shows that a rotor 60′ having a central hollow space 63 can beused, with the drive shaft 8 passing through the hollow space 63 fromits proximal side up to the distal end. The drive shaft 8 is thereconnected in a pull-resistant manner to a connection element 64 whichcan in turn be journalled in a rotatable and pull-resistant manner inthe bearing 53. The bearing can be made as a pull-resistant or as anon-pull resistant bearing.

A pressure can be exerted onto the rotor 60′ by means of the drive shaft8 in the direction of the arrow 65. A pull is correspondingly exertedvia the connection element 64 onto the distal end of the rotor 60′ inthe direction of the arrow 66. At the proximal end of the rotor 60′, thelatter is rotatably journalled in a pull-resistant manner in a bearing67 which is in turn non-displaceably fastened to the distal end of thehollow catheter 1. A pull can correspondingly be applied via thisbearing 67 onto the proximal end of the rotor in the direction of thearrow 68, whereby the rotor 60′ as a whole is stretched in thelongitudinal direction. Alternatively, the rotor can also be rotatablyjournalled at its proximal end in a pull-resistant manner in the housingand the housing can be axially fixed with respect to the catheter.

The rotor is compressed or is at least more simply compressible in thetransverse direction due to the different technical possibilitiesdescribed in connection with the invention of applying a longitudinalstretching onto the rotor. Corresponding impeller blades can likewisealso be stretched and/or brought into a more easily compressible state.The invention thus allows a better compressibility of the rotor and ofthe fluid pump as a whole.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1-16. (canceled)
 17. A method for inserting an intravascular fluid pumpinto a patient, the method comprising: compressing a rotor within a pumphousing of the intravascular fluid pump by elastically stretching therotor in a direction of a longitudinal axis of the rotor such that adiameter of the rotor decreases; inserting the pump housing into a bloodvessel of the patient; positioning the pump housing in a position in thevasculature of the patient; and expanding the rotor at the position inthe vasculature of the patient.
 18. The method of claim 17, furthercomprising applying a force in mutually opposite directions at differentends of the rotor to elastically stretch the rotor.
 19. The method ofclaim 17, wherein the rotor comprises at least one impeller blade thatis elastically stretchable in the direction of the longitudinal axis,wherein, when the rotor is elastically stretched in the direction of thelongitudinal axis, the at least one impeller blade is elasticallystretched in the direction of the longitudinal axis such that astability of the at least one impeller blade is reduced.
 20. The methodof claim 17, wherein compressing the rotor within a pump housing furthercomprises elastically stretching the pump housing in the direction ofthe longitudinal axis of the rotor such that a diameter of the rotorchanges.
 21. The method of claim 17, comprising changing a diameter ofthe rotor by changing a length of the rotor.
 22. The method of claim 17,comprising applying a force in mutually opposite directions at differentends of the pump housing to elastically stretch the pump housing suchthat a diameter of the pump housing changes.
 23. The method of claim 17,wherein expanding the rotor in the position in the vasculature comprisesradially expanding the rotor such that a diameter of the rotorincreases.
 24. The method of claim 17, further comprising transportingthe rotor through a portion of the blood vessel in a compressed state.25. The method of claim 17, further comprising sizing the pump housingto fit the rotor in an expanded state when the pump housing is in arelaxed state.
 26. The method of claim 17, wherein the pump housing isin a relaxed state when the pump housing is not stretched in a directionof a longitudinal axis of the pump housing.
 27. The method of claim 17,further comprising compressing the pump housing via an inflow funnel ofa hollow tube of the intravascular fluid pump.
 28. The method of claim17, further comprising actuating the intravascular fluid pump after therotor is expanded.
 29. The method of claim 28, further comprisingremoving the intravascular fluid pump from the patient after actuatingthe intravascular fluid pump.
 30. The method of claim 17, wherein therotor is disposed within a hollow tube of the intravascular fluid pumpduring insertion of the pump housing into the blood vessel of thepatient and expanding the rotor in the position in the vasculaturecomprises moving the hollow tube relative to the rotor such that therotor expands from a radially compressed state to a radially expandedstate.
 31. The method of claim 30, wherein the diameter of the rotor issmaller in the radially compressed state than the diameter of the rotorin the radially expanded state.
 32. The method of claim 17, wherein theinsertion of the intravascular fluid pump into the blood vessel is apercutaneous insertion.
 33. The method of claim 17, wherein theintravascular fluid pump comprises a first element and a second elementthat are coupled to the rotor and each configured to act axially on therotor to elastically stretch the rotor in the direction of thelongitudinal axis.
 34. The method of claim 33, wherein the first elementis coupled to the rotor via the pump housing.
 35. The method of claim33, wherein the second element is a drive shaft.
 36. The method of claim33, wherein the first element is a distal bearing.